Non-linear optical and electrical properties of germanate glasses
- a Physics and Engineering Mathematics Department, Faculty of Electronic Engineering, Menufiya University, Menouf 32952, Egypt
- b Physics Department, Faculty of Science, Menufiya University, Shebin El-Koom 32511, Egypt
- Received 23 March 2013
- Revised 24 July 2013
- Accepted 26 July 2013
- Available online 2 August 2013
Abstract
Glasses in the system Na2O–GeO2 were prepared via melt quenching technique. The optical absorption spectra were measured in the wavelength range from 190 to 1000 nm. The fundamental absorption edge for all the glasses was analyzed in terms of the theory proposed by Davis and Mott. The position of the absorption edge and hence the value of the optical band gap were found to show anomalous behavior depending on the glass composition. The absorption in these glasses is believed to be associated with indirect transitions. The origin of the Urbach energy is associated with phonon-assisted indirect transitions. The temperature-dependence of DC conductivity for these glasses has been examined in the temperature range 463–623 K. It reveals that the obtained activation energy (0.04–0.54 eV) of these glasses was glass composition dependent.
